I have to disagree with Craig about PC's not being able to do it. I kept mine under 220w of pc, and got great growth. My buddy has 2x 6" crocea's that he got from me when they were 2", and they're under 4x 96w in a 55g, plus they live on the sand bed. Currently, my 29g has 246w of pc (4x 55w 2sx 13w), and you wouldn't believe the growth I get. Funny thing is, I'm going to upgrade to a 150 HQI with 2x 55w pc's, but only to get my acro's to color up even more and for the color temp. I love 20k and I can't really achieve that with PC's, or at least not to my liking.